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Plants
Junior Science
Easy to read
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1
1a
All plants belong
to the same kingdom
(Plantae). Plants
are called
autotrophs, which
means they make
their own food
through the process
of photosynthesis
which also produces
sufficient oxygen
to the atmosphere
to allow all living
organisms to
respire. Plants
have laid down the
fossil fuels that
provide humans with
energy.
Every other animal
relies on plants
The Plant Kingdom
Plants grow mainly on land but also
can be found in the oceans and fresh
water. They have been on Earth for
millions of years. Plants species
currently number about 260,000.
1a
The Plant Kingdom – the main Phylum (Groups)
Ferns
Flowerin
g Plants
Ginkos
Plant
Kingdom
Mosses
Cycads
Conifer
s
Liverworts
Horsetail
s
1b
Plants as Producers
Plants are special
because they have
leaves and are able
to produce their own
food by the process
of photosynthesis
from sunlight using
raw materials that
they get from the air
and soil.
Plants can be thought
of as ‘food
factories’ which
provides most living
organisms on Earth
with a source of
energy and nutrients.
They produce the
energy that is at the
start of any food
chain and therefore
1c
The structure and functions of parts of the plant
The Shoot System
Above ground (usually)
Lifts the plant above
the soil
Main functions include:
Leaves photosynthesis
Flowers - reproduction
Fruit – seed dispersal
Stem - food and water
transport
The Root System
Underground (usually)
Anchor the plant in the
soil
Main functions include:
Absorb water and
nutrients
2c
Plants take up water through root hairs
Water moves into the plant through root hairs. Water being
drawn up the plants xylem due to transpiration decreases the
pressure inside the root hair cells and this negative
pressure pulls water in.
2c
Osmosis is the diffusion of water molecules through
a partially permeable membrane (extension)
Diffusion
means that the
net movement
of particles
(molecules) is
from an area
of high
concentration
to low
concentration.
Oxygen, Carbon
Dioxide and
water move
across the
cell membrane
by diffusion.
2c
Osmosis is the diffusion of water molecules through
a partially permeable membrane (extension)
Osmosis is the diffusion of water only through a
partially permeable membrane from where water is in
higher concentration to where it is in lower
concentration. (or where the solute is in higher
concentration)
2d
The process of transpiration
Transpiration is the process
their leaves.
Water enters a plant through
the underside of leaves, are
and O2 to diffuse out, water
out.
where plants lose water from
root hairs. When stomata, on
open to allow CO2 to diffuse in
vapour evaporates and diffuses
extension
2d
The process of transpiration
1. Water enters plant through root hairs by osmosis –
high to low concentration of water. 2. Attraction
between water particles pulls water up the plant
through the xylem. 3. Water evaporates from the leaves
through transpiration.
GZ Science Resources 2014
extension
2d
The process of transpiration
extension
The xylem transports water and the phloem transports
the products of photosynthesis
2d
Transport water
around the plant
Special features
>Cells join into
long and tube-like
hollow vessels.
>Cells have no end
walls, so form a
'pipeline'
carrying water
from leaves to
root.
>Spirals and rings
of lignin
surrounding the
cells strengthen
the walls, to
withstand pressure
extension
of water.
The xylem transports water and the phloem transports
the products of photosynthesis
2d
The xylem is probably the longest part of the pathway that water
takes on its way to the leaves of a plant. It is also the path of
least resistance, with about a billion times less resistance than
cell to cell transport of water.
Xylem cells are called
tracheids (cells with
narrower diameters) or
vessels (cells with
wider
diameters). Their cell
walls contain cellulose
and lignin making them
extremely rigid. Xylem
cells contain no
membranes and are
considered dead. These
cells overlap to create
a series of pathways
that water can take as
it heads to the
leaves. There is no
single column of xylem
extension
cells carrying water.
2d
The role that stomata have in the process of
transpiration
Stomata are
normally found
only on the
under or shaded
sides of leaves.
Their function
is to capture
CO2 from the
atmosphere by
exchanging water
for carbon
dioxide. The
exchange is
accomplished by
having water
directly open to
air to
facilitate the
capture.
extension
2d
The role that stomata have in the process of
transpiration
extension
Leaves are the main site of
photosynthesis. They make food
from carbon dioxide and water in
the presence of light. As stomata
open in the presence of light,
carbon dioxide will diffuse into
the leaf and at the same time,
water vapour will exit the leaf
through the stomata to the
surrounding atmosphere through
the process of transpiration.
Plants will lose water vapour
while taking up carbon dioxide
through their stomata. If this
water loss is uncontrolled,
plants can deplete their water
reserve.
Stomata prevent water loss from
the stoma by closing once the
2d
Plant features that control transpiration
The structure of a plant influences the rate of
transpiration. These features can reduce the rate of
water loss from the plant.
cuticle
boundary
A layer of
non-moving air
around the
leaf surface
that decreases
water loss.
Hair can
increase
boundary size.
A waxy
waterproof
layer on
plant
epidermis
to prevent
water loss.
stomata
extension
Pores in the plant that
can be closed to stop
plant transpiration
2e
Aquatic environment adaptations
boundary
>Unimportant to
increase
boundary as
mostly
surrounded by
water and
reducing
transpiration
not an issue
> Many have
large leaves to
maximise light
collection
because they do
not have to
reduce their
surface area
exposed for
stomata
>many do not
have stomata as
they use energy
to open and
close
>if they have
stomata they are
on the upper
part of the leaf
in contact with
the air
(especially in
cuticle
floating plants)
> Thin cuticle or none at all because
water retention not necessary.
> Some have thin cuticle to prevent
algae growth and allow water to roll
extension
off
2e
Temperate environment adaptations
boundary
> Larger leaves are
often found on
plants in the
undergrowth (also
because of low
light levels to
collect more light)
and smaller leaves
on plants exposed
to wind – the less
surface area the
less boundary to
protect.
> Some plants will
lose there leaves
(and reduce
boundary) during
winter when water
is limited.
stomata
>stomata have
active guard cells
that are triggered
to close by high
CO2 in the plant
and low water
levels in the
plant or soil.
>closing and
opening of the
stomata uses
cuticle
active transport
(ATP) so comes at
cost.
> A cuticle of wax around athe
plant is
present to prevent water loss through the
epidermis layer of the leaves and stem.
The wax is water repellent but
transparent so still allows light
to
extension
2e
Desert environment adaptations
boundary
stomata
> Many plants have fine
hairs on their epidermis
to reduce air movement
and increase the size of
their boundaries – moist
air is also trapped in
the hairs
> Often their stomata
are sunken in pits
(crypts) or in
channels
> Some plants can open
their stomata at night
(C4 plants) to get CO2
> Leaves can roll up
for photosynthesis – a
tightly and reduce
special dark process
surface area available
that doesn’t directly
for transpiration
need light.
Transpiration is much
> Have very small
cuticle
reduced in this cooler
leaves, reduced them to
dark environment.
spines or lost them > Often very thick, leathery
and tough –
completely
covering the entire leaf and plant.
> the thick cuticle is shiny and reflects
light lowering the temperature extension
3a
The significance of photosynthesis in making food
Most living
organisms depend on
plants to survive.
Plants convert
energy from sunlight
into food stored as
carbohydrates
through
photosynthesis.
Because animals
cannot make their
own food they must
eat plants to gain
nutrition. Plants
produce oxygen,
which is released
during
photosynthesis,
3a
The adaptations of leaves for photosynthesis
The flat surface of the leaf
called the blade helps capture
maximum sunlight for
photosynthesis.
The leaf is attached by a
stem-like petiole to the plant
which branch out into veins.
Inside these are xylem tubes
to transport water to the leaf
cells, which they require for
photosynthesis and to keep the
leaf cells turgid or rigid.
The veins also contain phloem
tubes which are able to
transport the sugars (and
starch which they are
converted into), produced
during photosynthesis, away
to other parts of the plant
for use and storage.
3a
The adaptations of leaves for photosynthesis
A waxy cuticle on the
outside of the leaf
provides a waterproof
covering while
remaining transparent
to allow light into
the leaf cells for
photosynthesis.
Openings (usually on
the underside of the
leaf) called stomata
allow carbon dioxide
to enter and diffuse
into cells as well as
allowing oxygen to
move in and out.
Two guard cells on
either side of the
stomata open and close
extension
the openings.
Photosynthesis transfers energy from sunlight into
energy in chemicals such as glucose and starch.
3b
Light enters the leaf and
is trapped by chlorophyll
contained within the
chloroplasts in the
cells.
Water is transported via
xylem to the cell and the
carbon dioxide enters
through the stomata and
diffuses to the cell.
These substances react
chemically within the
chloroplasts, powered by
the light and glucose (a
sugar) is produced along
with oxygen which
diffuses out. The sugar
leaves the leaf via the
Carbon dioxide + Water +light
→ Glucose + Oxygen
phloem.
3d
The structure of a leaf enables photosynthesis to
occur effectively
The cells at the top of the leaf are filled with
chlorophyll, which gives leaves the green colour. The
chlorophyll allows the leaf to absorb light energy which
is required for photosynthesis. The spaces between cells
in the spongy mesophyll allow carbon dioxide to diffuse
around through the cells.
extension
3d The
leaf structure and types of cell inside a leaf
Cuticle: Waxy layer water proofing upper
leaves.
Upper epidermis: Upper layer of cells. No
chloroplasts. Protection.
Vascular Bundle: Bundle of many vessels
(xylem and phloem) for transport. Xylem:
Living vascular system carrying water &
minerals throughout plant.
Phloem: Living vascular system carrying
dissolved sugars and organic compounds
throughout plant.
Palisade Mesophyll: Tightly packed upper
layer of chloroplast containing cells.
Spongy Mesophyll: Lower layer of cells.
Air space: Area for gases to disperse
Lower Epidermis: Lower external layer of
cells in leaf.
extension
Stomata: Opening between guard cells for
gas & water exchange.
Guard Cells: 2 cells surrounding stomata
that control rate of gas & water exchange.
3e
Starch test
When a plant
undergoes
photosynthesis
it produces
glucose which
is converted
into starch for
storage. If we
want to
investigate
what factors
are required
for
photosynthesis
we use the
starch test to
enable us to
reach a
conclusion.
extension
4a
The parts of the flower and the role of the flower
in pollination, seed production and dispersal
Plants that
produce
flowers are
known as
angiosperms.
The flowers
are the
reproductive
structures
where
fertilisatio
n occurs and
seeds are
produced.
4a
The reproductive parts of an insect-pollinated
flower
Insect-pollinated
flowers have
visible, often
colourful petals
that surround the
flower's sexual
reproduction parts.
The petals can
"advertise" for
specific pollinators
through their shape,
size, colour and
sometimes smell. The
flowers are
surrounded by
sepals, which are
small and usually
green structures
that protect the
flower as its
4a
The reproductive parts of an insect-pollinated
flower and their function
The female part
of the flower is
called the
pistil. The
pollen from a
male part of a
flower is
brought to the
stigma by a
pollinator. This
process is
called
pollination.
The pollen
travels down the
style into the
ovary to join
with an egg cell
inside the
The male part
of a flower is
called the
stamen. The
pollen is
produced in the
anther which is
held up by the
filament. The
pollen is
collected by a
pollinator. The
pollen contains
male gametes
which will
later fuse with
the female
gametes in the
ovule during
fertilisation.
4b
The reproductive parts of an insect-pollinated
flower and their function
Insect-pollinated
Flowers often contain
nectar, a sweet sugar
produced by the plant,
to attract an insect.
As the insect reaches
into the flower for
the nectar it may be
brushed with pollen
from the anther. If
the insect moves to
another flower it may
brush the pollen
against the stigma and
therefore pollinate
the flower.
Flowers ripen their
male and female parts
of the flower at
different times to
4b
Summary of pollination in plants
1. The male parts of the flower are the anther and filament
2. The female parts of the flower are the stigma, style and
ovary
3. Male gametes are found in Pollen Produced in the Anther
4. Pollen needs to be moved to the female part called the
Stigma of the same species of plant to reproduce
5. This process is called Pollination
6. Pollination can be helped by Wind Or Animal
7. An example of wind pollination is grass plants
8. A wind pollinated flower is most likely to look like
small, green, unscented
-
9. An example of animal pollination is a rose plant pollinated
by insects
10.An animal pollinated flower is most likely to look like –
colourful, with large petals, perhaps with a scent
4c
The differences in structure between insect-and
wind-pollinated flowers
Insect pollinated flowers
are easily seen and often
contain scent and nectar
to attract the insects.
The male parts are adapted
so they make contact with
the insect as it feeds
from the flower.
Wind pollinated flowers are
often small and green with
no scent. Male anthers
protrude out from the flower
to allow the wind to pick up
the pollen and disperse it
away from the plant. Male
and female parts develop at
different times.
4c
Examples of insect-pollinated flowers
GZ Science Resources 2014
4c
Examples of wind-pollinated flowers
GZ Science Resources 2014
4d
Fertilisation in flowering plants
1. Pollen from either the
same plant (selfpollination) or another
plant (crosspollination) needs to
arrive on the flowers
stigma
2. The pollen sends a tube
down the style to reach
the ovule, and the male
gametes (there are two
in every pollen grain)
enter the ovule to
fertilise the egg
(female gamete)
extension
3. One male gamete joins
with one female gamete
to form a zygote and the
plant is fertilised.
(The fertilised ovule
4d
The differences between pollination and
fertilisation in flowering plants
Pollination just
refers to pollen
landing on the
female stigma of
the plant. This
can either be with
a pollinator or
wind.
Fertilisation
refers to the
sperm cell (that
was in the pollen
grain) joining
with the egg cell
to form a single
cell (zygote).
Pollination does
not always lead
to
extension
fertilisation
5a The
formation of seed and fruit from ovule and ovary
Once the flower has
been fertilised by
pollen the ovary
grows to form the
fruit.
The ovules become the
seeds.
The outer part of the
ovule grows into the
seed coat. The zygote
grows into the young
plant – or embryo
A fruit may have one
or more seeds.
The petals, sepals
and other parts of
the flower start to
die and fall off.
5a
Seed dispersal
Pollen is dispersed (or spread) from plant to plant so the
flowers can be pollinated and fertilised seeds produced. Once
the Seeds are mature they then also need to be dispersed so
they are not competing with the parent plant for space, light,
water and nutrients. There are various ways that plants have
evolved to disperse their seeds; forming inside fruit that
animals will eat and spread, forming structures on the seed so
the wind will carry them away, can float away, be forced away
or tangle in the coat of an animal to be carried away.
5a
Seed dispersal
How are seeds dispersed?
By animals
By the wind
Self dispersal
5b
The conditions needed for germination of seeds
Seeds will remain dormant until they receive
water
warmth
light
oxygen
Then they will germinate.
Other types of seeds may also require
>fire to burn seed coat
>soaking in water
>scratched seed coat
>being digested by animals
Before they germinate
5b
The conditions needed for germination of seeds
Testa
Plumule
(embryo
shoot)
Radicle
(embryo root)
Micropyle
The seed contains
the embryo plant
and cotyledons
(starch stores)
Water enters the
seed through the
micropyle and
activates enzymes.
The water also
softens the testa
to allow it to
split.
Cotyledon
5b
The conditions needed for germination of seeds
Plumule
starch
embryo plant
amylase
secreted
maltose
Radicle
This is the
first part to
grow out of the
seed as it
needs to absorb
more water
The enzymes
break starch
down into
maltose and
then glucose.
The glucose is
used in
respiration to
provide energy
for growth
5b
The conditions needed for germination of seeds
Whilst
germinating
the plant uses
food stores in
the cotyledon
to provide
energy for
growth
germination
The seedling
can now
photosynthesis
e and make its
own food
Plant growth and development
5b
The conditions needed for germination of seeds
Seed loses weight as it
uses up starch stores in
the cotyledons as the
seedling cannot
photosynthesise yet
Dry mass/g
Dry mass is
the mass of
solid
matter with
all water
removed
Weight
increases as
the seedling
can
photosynthes
ise and
plant grows
Days
5b
The conditions needed for germination of seeds
Summarise the findings of the experiment shown
below: (absorbs oxygen)
Pyrogallol
No light
Oxygen
presen
t
Oxygen
presen
t
Oxygen
presen
t
Oxygen
presen
t
No
oxygen
moist
4oC
A
dry
moist
moist
Warm
B
Warm
C
Warm
D
moist
Warm
E
5c
The structure of a seed
The seed consists of
the seed coat or the
testa which
surrounds the
cotyledons or the
food storage area.
The embryo consists
of the radicle which
is the embryonic
root and the
hypocotyl which
forms the first
shoots and leaves of
the plant. A small
pore in the seed may
be seen called the
micropyle. This is
where the pollen
originally entered